Although the text-tool in GIMP works right now, it could be even better and more convenient with more functionality. When editing text you type the text in a dialog instead of on the canvas itself. I found "on-canvas text editing" as one of the ideas listed on the GIMP GSoC ideas page, and thought it would be a good idea to implement, as it would make the text tool more ergonomic and also look a little better (less dialogs to keep track off = cleaner interface).

The first thing I would do would be to port the GIMP text core to pangocairo (it's using pangoft2 right now), increasing functionality with GIMP since it's using Cairo. I would then tackle the actual on-canvas editing (which would pretty much be the main idea), and depending on the time it would take, check out the possibilites for adding text styles while editing this way (possibly allowing multiple styles per text layer).

Many thanks to the people in #gimp for helping me discuss this idea.